1. Field of the Invention
The present invention relates to a method of collectively connecting multiple optical connectors and an aligning and positioning jig for multiple optical connectors which is used in this method.
2. Description of the Related Art
FIG. 28 shows an example of the connection of optical fiber cables of an optical communications network using optical connectors. In FIG. 28, each optical connector 1 comprises a multifiber ferrule 2 attached with a multi-optical fiber ribbon 3. The multifiber ferrule 2 has a plurality of through holes 4 for the insertion of optical fibers, arranged at equal pitches in the horizontal direction (in the widthwise direction of the ferrule). The through holes 4 penetrate to a connection end face 5 on the distal end side from the proximal end side. The individual optical fibers of the multi-optical fiber ribbon 3 are securely fitted in the respective through holes 4 and their free ends are polished together with the connection end face 5.
A pair of pin holes 6 which are open to the connection end face 5 are formed in the multifiber ferrule 2 on both sides sandwiching the through holes 4. Fitting pins (guide pins) 7 are fitted in the respective pin holes 6, and the free ends of the fitting pins 7 are then fitted in the respective pin holes 6 of the mating optical connector 1. Accordingly, the connection end faces 5 of the two optical connectors 1 abut on each other, and the individual optical fibers of the multi-optical fiber ribbon 3 of one optical connector 1 are coaxially connected to the individual optical fibers of the multi-optical fiber ribbon 3 of the other optical connector 1.
Under this state, a clamp spring 8 is attached to both the optical connectors 1,1 so that spring-force applying portions 10 of the clamp spring 8, which applies the elastic restoring force, is press-fitted on rear end faces 11 of the multifiber ferrules 2. Then, this spring force presses the multifiber ferrules 2 in such directions as to press-fit the connection end faces 5 against each other, thereby stably keeping the connection of the optical connectors 1,1.
Recently, there is an increasing demand for optical fiber cables as the multifunction capability of optical communications networks is improved. As the demand for optical fiber cables increases, an attempt is made to increase the number of optical fibers of each optical fiber cable. Under this situation, the system of connecting multiple optical fibers in optical fiber cables by fitting two optical connectors 1 to each other has a poor working efficiency. In connecting 1000 optical fibers comprising 250 4-optical fiber ribbons, for example, the connection of optical connectors 1 pair by pair requires 250 pairs of optical connectors and repeating the task of connecting the optical connector pair 250 times. This increases the ratio of the fitting of the optical connector pair in the entire connecting work, resulting in a poor working efficiency. With this system, therefore, it is difficult to cope with the recent trend of increasing the number of fibers of each optical fiber cable.
In view of the above, there are made studies on high fiber density with an increased number of optical fibers to be attached to the optical connector 1 and on the collective connection of multiple optical connectors 1 at a time. FIG. 27 shows one example of multi-layered connector which can ensure such collective connection.
The multi-layered connector shown in FIG. 27 has a box-like housing 13 having an opening 12 formed in the front end face, multiple optical connectors 1 retained in lamination in the housing 13 through the opening on the rear end side, and pin holes 9 formed in the four corners of the front end face of the housing 13.
The collective connection of a plurality of optical connectors is accomplished by connecting one group of optical connectors laminated in one housing 13 with fitting pins inserted in the pin holes 9, to another group of optical connectors laminated in another housing 13 in such a manner that the connection end faces 5 of the optical connectors in one housing 13 are positioned to abut on the associated connection end faces 5 of the optical connectors in the other housing 13, by fitting the fitting pins protruding from one housing 13 into the pin holes 9 in the other housing 13 and fitting the fitting pins 7 on the optical connectors in one housing 13 into the pin holes 6 (see FIG. 28) of the optical connectors in the other housing 13.
The multi-layered connector shown in FIG. 27 allows for the collective connection of multiple optical connectors 1, thereby significantly improving the working efficiency for connecting multiple optical fibers of an optical fiber cable.
Because the multi-layered connector shown in FIG. 27 is designed to collectively connect one group of optical connectors placed in lamination in one box-like housing 13 to another group of optical connectors placed in lamination in another box-like housing 13, the housings 13 cannot be removed after the optical connectors are collectively connected to the mating optical connectors. The optical-connector jointing portion of the multi-layered connector shown in FIG. 27 bulges, so that the bulging optical-connector jointing portion occupies extra space particularly when the multi-layered connector is accommodated in a closure.